Field of the Invention
The present invention relates to a device and method for controlling the position of an object to be controlled according to feedback control and feedforward control, and an optical device and an image pickup apparatus using the same.
Description of the Related Art
A servo control system that performs feedback control based on detection information of an absolute position of a object to be controlled and performs feedforward control according to a target value of the object to be controlled is known. Japanese Patent Laid-Open No. H03-289385 discloses a servo control system capable of calculating a feedback gain from a feedforward gain and automatically adjusting the feedback gain. Moreover, Japanese Patent No. 4673326 discloses a position control device that performs adaptive identification to correct the parameters of feedback control and feedforward control.
In Japanese Patent Laid-Open No. H03-289385, it is assumed that a controller is installed in a fixed coordinate system. When an installed attitude of the entire apparatus changes, the controller calculates a feedforward output based on a change in a target value. However, force that balances against the force associated with the attitudinal change causes a loss or surplus of force. Thus, an intended accelerating force is not generated, and depending on the amount of an attitudinal change, the velocity may change when a driving direction changes.
In Japanese Patent No. 4673326, it is assumed that the control device is installed in a fixed coordinate system. When an attitude in which the entire apparatus is installed changes, adaptive identification is performed based on a driving command applied to a driving unit. However, a driving command component for resisting an attitudinal change becomes a bias component. Thus, an identification error may occur depending on the amount of an attitudinal change when the apparatus is in an attitude other than a horizontal attitude.